Prospect of biopolymer application for sustainable and durable earthen structures in context of Bangladesh: A brief review Available to Purchase

While infrastructural developments all over the world are going at an unprecedented speed, a significant number of poor people still live in the mud houses in rural areas in many parts of the world. Although earthen structures are seen all over Bangladesh, there is no specific building code for these houses. Lack of codes and guidelines lead to a non-standard construction of these low-cost housings. Since earthen houses are exposed to severe degrading and degenerating agents, predominantly water, it has been seen in the past that during natural calamities they are short lived and fall apart and as a consequence they fail to protect the dwellers. Earthen structures mostly fail due to issues of durability rather than strength. Conventional admixtures such as fly ash, cement, lime, etc., have been combined with earthen building blocks to improve their properties, but they increase CO2 emission as consequence due to their inherently huge carbon footprint. Several studies on the suitability and effectiveness of various biopolymers for soil improvement have been conducted in recent decades. Biopolymers are successively connected molecules composed of repeated chemical blocks derived from renewable resources that are susceptible to degradation in the environment. It has been observed that they are gradually replacing traditional admixtures in this application. In spite of increasing worldwide applications, no interest has been shown in our country in using biopolymers in earthen buildings. The purpose of this study is to investigate how biopolymers can be used to improve the characteristics of earthen buildings in providing a sustainable climate-resilient option for impoverished rural populations in Bangladesh. This review is based on the findings of almost 40 publications that address experiments on the durability, strength, thermal resistance, hygroscopic properties, and stability of earthen structures, mostly in the United Kingdom, Peru, France, Korea, as well as how biopolymers might bring changes in these properties. As Bangladesh is striving hard to achieve the Sustainable Development Goals (SDG), introducing Biopolymers in Earthen structure will lead to the development of sustainable infrastructures. Thus, we surely will be one step closer to reaching this SDG goal. The literatures mostly agree that introducing biopolymer in earthen structures is typically more environmental-friendly, more structurally stable, and more thermally pleasant than treatment using traditional admixtures, particularly cement. The government may introduce these improved earthen structures to rehabilitate residents who have lost their homes in disaster-stricken areas or relocation projects for major constructions. We have highlighted the potential areas for further research in assessing various governing parameters in the context of Bangladesh that can bring new room for discussion in this aspect.